Do they mention ways to "enlighten" yourself from such a state?
I am such a novice at this, I have to say!
But I have read this:
Denourishing of Sloth and Torpor
There is the element of rousing one's energy, the element of exertion, the element of continuous exertion; frequently giving wise attention to it — this is the denourishing of the arising of sloth and torpor that have not yet arisen and of the increase and strengthening of sloth and torpor that have already arisen.— SN 46:51
"May nothing remain but skin and sinews and bones; may flesh and blood dry up in the body! Not before having achieved what can be achieved by manly strength, manly energy, manly exertion shall my energy subside!"
— MN 70
Six things are conducive to the abandonment of sloth and torpor:
Knowing that overeating is a cause of it;
Changing the bodily posture;
Thinking of the perception of light;
Staying in the open air;
Noble friendship;
Suitable conversation.
These things, too, are helpful in conquering sloth and torpor:
The recollection of Death To-day the effort should be made, Who knows if tomorrow Death will come? — MN 131
Perceiving the suffering in impermanence
In a monk who is accustomed to see the suffering in impermanence and who is frequently engaged in this contemplation, there will be established in him such a keen sense of the danger of laziness, idleness, lassitude, indolence and thoughtlessness, as if he were threatened by a murderer with drawn sword.— AN 7:46
Sympathetic joy
Cultivate the meditation on sympathetic joy! For by cultivating it, listlessness will disappear.— MN 62
Contemplation of the spiritual journey"I have to tread that path which the Buddhas, the Paccekabuddhas and the Great Disciples have gone; but by an indolent person that path cannot be trodden."— Vism. IV,55
Contemplation of the Master's greatness"Full application of energy was praised by my Master, and he is unsurpassed in his injunctions and a great help to us. He is honored by practicing his Dhamma, not otherwise."— Ibid.Contemplation on the greatness of the Heritage"
I have to take possession of the Great Heritage, called the Good Dhamma. But one who is indolent cannot take possession of it."— Ibid.
How to stimulate the mind
How does one stimulate the mind at a time when it needs stimulation? If due to slowness in the application of wisdom or due to non-attainment of the happiness of tranquillity, one's mind is dull, then one should rouse it through reflecting on the eight stirring objects. These eight are: birth, decay, disease and death; the suffering in the worlds of misery; the suffering of the past rooted in the round of existence; the suffering of the future rooted in the round of existence; the suffering of the present rooted in the search for food.— Vism. IV,63
How to overcome sleepiness
Once the Exalted One spoke to the Venerable Maha-Moggallana thus: "Are you drowsy, Moggallana? Are you drowsy, Moggallana?" — "Yes, venerable sir."(1) "Well then, Moggallana, at whatever thought torpor has befallen you, to that thought you should not give attention, you should not dwell on it frequently. Then it is possible that, by so doing, torpor will disappear.(2) "But if, by so doing, that torpor does not disappear, you should think and reflect within your mind about the Dhamma as you have heard and learned it, and you should mentally review it. Then it is possible that, by so doing, torpor will disappear.(3) "But if, by so doing, that torpor does not disappear, you should learn by heart the Dhamma in its fullness, as you have heard and learned it. Then it is possible...(4) "But if, by so doing, that torpor does not disappear, you should shake your ears, and rub your limbs with the palm of your hand. Then it is possible...(5) "But if, by so doing, that torpor does not disappear, you should get up from your seat, and after washing your eyes with water, you should look around in all directions and look upwards to the stars in the sky. Then it is possible...(6) "But if, by so doing, that torpor does not disappear, you should firmly establish the (inner) perception of light: as it is by day, so also by night; as it is by night, so also by day. Thus with a mind clear and unobstructed, you should develop a consciousness which is full of brightness. Then it is possible...(7) "But if, by so doing, that torpor does not disappear, you should, conscious of that which is before and behind, walk up and down, with your senses turned inwards, with your mind not going outwards. Then it is possible...(8) "But if, by so doing, that torpor does not disappear, you may lie down on your right side, taking up the lion's posture, covering foot with foot — mindful, clearly conscious, keeping in mind the thought of rising. Having awakened again, you should quickly rise, thinking: 'I won't indulge in the enjoyment of lying down and reclining, in the enjoyment of sleep!'"Thus, Moggallana, you should train yourself!"— AN 7:58
http://www.accesstoinsight.org/lib/authors/nyanaponika/wheel026.html#sloth
Sorry so long and messily done on my phone.